Mobile phones generally comprise software applications that may be executed to operate the mobile phone. In addition to enabling a phone with voice communications capabilities, these software applications may enable a phone with various other capabilities, such as text messaging and digital photography. A mobile phone boot image may comprise an operating system and any of a variety of such software applications that may be executed on the mobile phone. The price of a mobile phone may vary based on the quality of the boot image embedded in the phone's flash memory. High-quality boot images may cause particular phones to be more expensive than phones with boot images of lesser quality.
Texas Instruments'® proprietary Open Multimedia Applications Platform (“OMAP”) comprises a microprocessing engine that enables communications devices to process data and software applications while extending battery life. A mechanism present in current OMAP devices (i.e., models 161x, 171x, 73x) supports the flashing and booting of boot images using a key that is shared among a plurality of devices. This key helps verify the authenticity of a boot image, but does not prevent the unauthorized copying and re-use of the boot image on a separate phone, resulting in a possible penetrable security gap. Such a security gap may enable unauthorized entities to copy boot images from expensive phones and reproduce the boot images on inexpensive phones. In this way, an unauthorized entity may clone an expensive phone into an unlimited number of inexpensive phones and sell the inexpensive phones for a profit.
In addition to unlawfully copying the boot image, unauthorized entities also may tamper with the contents of the boot image to circumvent existing safeguards that prevent the usage of stolen mobile phones. For example, each mobile phone boot image comprises an International Mobile Equipment Identifier (“IMEI”) number that serves as an identification code for the phone in the Global System for Mobile Communication (“GSM”) and Third Generation (“3G”) networks. The IMEI number is used to grant or deny access to the cellular networks and the networks' services. Generally, if a phone is stolen, the owner may contact his or her cellular service provider (e.g., Sprint®, Verizon®, AT&T®) and have the phone added to a GSM/3G blacklist. Mobile phones found on the blacklist will be denied access to the cellular networks. Thus, an unauthorized entity that steals the phone would not be able to use the phone to access the networks, because the IMEI number of the phone has been added to the blacklist. However, a knowledgeable, unauthorized entity may easily alter the IMEI number of the stolen phone to a number that is not found on the blacklist, thereby gaining access to the cellular networks by way of the stolen phone.
Each year, mobile phone manufacturers lose substantial amounts of revenue due to phone cloning and tampering. Thus, it is desirable to prevent phone cloning and tampering.